Cognition · 5 min
Cognitive health and dementia prevention
The 2024 Lancet Commission on dementia identified 14 modifiable risk factors that, in aggregate, account for roughly 45% of dementia cases worldwide. The implication is striking: dementia is, to a meaningful degree, a preventable disease — provided prevention starts in midlife, not at the first lapse.
The 14 levers
Less education in early life; hearing loss, hypertension, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol, traumatic brain injury, air pollution, social isolation, untreated visual impairment, and high LDL cholesterol in midlife. The largest single contributors are hearing loss, low education, smoking, and hypertension.
Why midlife matters
Pathological changes in Alzheimer's begin 15–20 years before symptoms. Vascular contributions to dementia compound across decades. The interventions that move the needle — controlling blood pressure to <130/80, treating hearing loss, exercising, sleeping well, maintaining ApoB — work because they act before the brain has been quietly remodelled.
What the strongest evidence supports
Aerobic fitness and resistance training (FINGER trial), tight blood pressure control (SPRINT-MIND), correction of hearing loss (ACHIEVE), social engagement, adequate sleep, a Mediterranean dietary pattern, and avoiding head injury. None are dramatic in isolation. Stacked over twenty years, they shift the curve.
What to do this decade
- Get hearing tested at 50, and again every few years. Wear hearing aids if needed.
- Treat blood pressure to <130/80 — it is the single most under-treated dementia risk factor.
- Train aerobically and lift weights, weekly, without exception.
- Protect sleep, social ties, and intellectual engagement as if they were medications.
- Wear a helmet on bikes, skis and motorbikes — TBI is permanent.